Nguyễn Xuân Tuyên

Tạo và quản lý user - linux

Wednesday, May 5, 2010 4:41:28 AM
1. Giới thiệu chung

Khi thêm một user vào hệ thống, người quản trị cần biết vai trò của các tập tin sau (trong thư mục /etc ): passwd, shadow, group, gshadow
/etc/passwd: chứa thông tin của tất cả các user: login name, user ID, Group ID, Full Name, Home directory, loại shell
/etc/shadow chứa các thông số điều khiển quá trình user login: user password (dạng hash, không đọc được), và thông tin thời hạn mật khẩu
/etc/group chứa thông tin về group của users
/etc/gshadow chứa password của group dưới dạng hash (ít khi dùng đến).

Files (Text Base)

Create new file

#nano filename
#nano /etc filename
#touch filename
#touch /etc filename

To edit file

#nano filename

Read file

#nano filename
#cat filename
#cat filename |more

Read first 10 lines

01. Last thousand command display
[root@server ~]# history |more

02. Last ten command display
[root@server ~]# history 10

Once you logout or shutdown your pc your current command history will be saved in to a hidden file in your home folder.

03. See a hidden file
[root@server ~]# cd
[root@server ~]# cat .bash_history


4. To clear History
[root@server ~]# ln -sf /dev/null ~/.bash_history
[root@server ~]# >~/.bash_history


5. Another
1) Another option is link ~/.bash_history to /dev/null:
ln -sf /dev/null ~/.bash_history

2) The sintax is wrong, it shoud say:
ln -sf /dev/null ~/.bash_history

By default any Linux system will fully support FAT partitions, But when it comes to NTFS some are still NOT supporting by default.

Desktop Editions such as Ubuntu 7.10 and Fedora 8 now fully supporting NTFS (with write support), and the partitions are automatically mounted.

Server Editions such as CentOS 5 and RHEL 5 you have to do the following to access NTFS partitions.

01. Configure RPMFroge 3rd party repository, please read my tutorial about CentOS Repositories.

02. Install the following packages
[root@server ~]# yum install dkms-fuse fuse-ntfs-3g

Accessing the Windows partitions.

01. See what are the current partitions in your system, and figure out what partitions belongs to windows.

[root@server ~]# fdisk -l

Sudo is a program which can be used by normal users to execute programs as super user or any other user. Sudo access is controlled by /etc/sudoers. The users listed in /etc/sudoers file can execute commands with an effective user id of 0 and a group id of root's group.

The file '/etc/sudoers' should be edited with the editor "visudo".

01. First, create a user called "vihost"
#useradd vihost
#passwd vihost

02. To give a specific group of users limited root privileges, edit the file with visudo as follows:
# visudo

03. Go down to the line ‘# User privilege specification‘and add the following line.

uddika ALL=(ALL) ALL